Any info on the Hughes HM-4118 computer?

Many years ago I was trained on the maintainance of what was then an already vintage computer, the HM-4118. This was an 18-bit mini with lots of core, totally mil-spec all the way down to a Klienschmidt teletype terminal. This computer needed to be rugged and dependable, it was the brain for a combat air-traffic control radar system. Built by Huge Aircrash, err, um, Hughes Aircraft, this system (called a TSQ-91) could be set up just about anywhere in the world (and often were) on short notice to provide command, control and communications capabilities, rather like an AWACS plane meets a MASH camp, in a kinda-mobile ground installation. The HM-4118 has got to be one of the most physically rugged blinkinlights mini's ever made. It was so overbuilt it could easily win any contest for 'most-ugly-mini', yet with its real-time, vector-graphic radar display overlays it was also the 'coolest' computer I've ever worked with (beating things like Connection Machines). Anyway, is there anywhere I could find info on the HM-4118, or god-forbid, ever find one of these beasts, or its ancestors? I do know of a stash of photographs of a TSQ-91 system in operation, some excellent quality slides. I should see about getting some of these scanned sometime....